While State Sen. Leah Vukmir expressed outrage that John Doe investigators cataloged some of her personal emails and Attorney General Brad Schimel said he did not understand why they would do that, the Doe investigators were just following good protocol, according to publications on digital investigations.

"If the case ever comes to trial, the investigator presenting the case must be able to prove ... the data was not modified during acquisition or analysis (chain of custody)," forensic analyst Michael Graves wrote in The Anatomy of a Digital Investigation.

Vukrmir (R-Brookfield), a candidate for U.S. Senate, said in a statement that “The upsetting news that my privacy was violated as personal emails between my daughter and I were obtained, read and kept by those who ran the John Doe investigation is absolutely appalling. This criminal behavior is inexcusable, and the individuals involved in this belong in prison."

Vukmir's emails were seized during the John Doe investigation into Gov. Scott Walker's campaign, according to Schimel's report, which indicated investigators had a warrant.

Vukmir

Attorney General Brad Schimel, in his new report on his Justice Department's investigation into the Doe investigation, said that Doe seized emails included "private medical information and other highly personal information. DOJ was unable to determine why investigators ever obtained, let alone saved and labeled, over 150 very private and very personal emails between a Senator and her child. ... ”

But Adam Stone, writing for Govtech Works, said, "One final word of advice from the FBI: Keep it all."

"Without the right protections, digital files can be easily deleted, edited, even fabricated," he wrote. "So documenting a digital chain of custody is all the more important. A compromised chain can undo a legal proceeding and lay waste to years of investigation. And all a defense attorney has to do is successfully raise concerns about potential tainting of evidence – that alone is enough, let alone demonstrating actual taint."

He quotes Patrick Zeller, a former high-tech prosecutor and litigator: "Because digital evidence is more susceptible to intentional or inadvertent alteration or destruction than many forms of evidence, it is critical that a witness be able to offer evidence upon which the judge can conclude that the data is in substantially the same condition as when it was seized."